Lightweight component for bearing elements of motor vehicles

ABSTRACT

A lightweight, plastic coated component is in the shape of a three-dimensional shaped part with a metal layer provided with access apertures through which the plastic may flow. The component includes stiffening ribs created by the plastic that are positioned within hollow areas of the three-dimensional shaped part, and whose plastic extends through the apertures of the metal insert. The component is formed as a metal insert spray-covered with plastic for the purposes of optimizing the plastic spray process and to achieve an inner bond between the metal insert and the stiffening ribs. The metal insert includes a large number of evenly-distributed holes, and these holes form a flow resistance and also a flow enabler for the molten mass of plastic during spraying. There are projections present at each of the holes that are covered by the plastic coating. The stiffening ribs facing away from the sprayed side have a connecting cross-section that extends into the metal insert via a number, or a large number, of holes in the metal insert.

TECHNICAL FIELD

The invention relates to a lightweight component and more particularly, to a lightweight component having a plastic coated metal insert. The metal insert includes holes and protrusions for controlling and enabling the plastic coating.

BACKGROUND INFORMATION

Lightweight components are known, for example, from DE 38 39 855 C2. The overwhelmingly closed-wall metal insert of this lightweight component consists of a shaped body of sheet metal that possesses large-format holes positioned at clear distances from one another. The stiffening ribs that consist of sprayed-on plastic positioned within the hollow region of the shaped part that extends through the holes in the shaped part to surround the hole edge are oriented to these holes. In this manner, discrete attachment points are formed for the stiffening ribs within the shaped part to which a form-fit connection exists between the plastic of the stiffening ribs and the metal.

In the known lightweight component, the shaped part consisting of metal sheet possesses considerable stiffness and provides a so-called foundation to determine the basic shape of the lightweight component. In order to make this shaped part more stiff against flexing and torsion, stiffening ribs sprayed on to discrete positions of the shaped part are provided whose positions are dependent on the positions of the holes in the shaped part. Because of the few holes in the shaped part and their considerable separation, the number of stiffening ribs is limited, and the formation of the connection point for the ribs may bear only a limited load. On the other hand, the relatively few holes in the metal shaped part are easily reached by the front of the molten flow.

Also, components are also known that are produced of plastic using injection molding and include a metal insert for stiffness. Spraying of stiffening ribs located within hollow regions of such components will not be discussed here. The point is that the permeability of the stiffening insert for the molten plastic in an injection-mold process may be easily adapted so that the stiffening insert is completely coated by plastic material during the injection process.

SUMMARY

It is one object of the present invention to create a lightweight component according to the overall concept that is optimized with respect to the flow conditions of the molten plastic during the injection process within the proper injection mold, and in which an inner bond exists between the metal insert and the plastic forming the stiffening ribs that also laminates the outer side of the lightweight component facing away from the stiffening ribs.

It is significant for the lightweight component based on the invention that the outer side of the metal insert facing away from the ribs is the injection direction that thus is sprayed from without with the plastic material. In order to be able to form the stiffening ribs at the same time on the inner side of the metal insert facing away from the spray direction in the pertinent injection-molding tool, the special sieve structure of the metal insert is used to optimize the path of the molten plastic within the injection-molding tool. Here, the main point is to achieve small-diameter openings by means of the large number of holes in the metal insert for the molten plastic that present an increased resistance to the injection pressure of the molten plastic during the injection process. Further, the formation of a flow split on the injection direction of the metal insert facing the tool wall is important.

First, the molten plastic may exert a force from without on the metal insert, because of which the inner side of the metal insert is preferably matched to the inner side of the injection mold. Thus, independent of whether the fluid plastic completely infiltrates the inner side of the metal insert, the lightweight component may be formed with flat inner sides. Second, the molten mass seeks the path of least resistance and fills the split-shaped cavity that exists between the outer side of the metal insert with the projections here at the holes and the outer wall of the injection mold. Thus, an enclosed coating of the metal insert is achieved on the outer side or the injection side by means of the plastic material. Further, the relatively small cross-sections of the holes in the metal insert make more difficult a too-rapid penetration of the molten plastic into the channels located within the injection mold below or behind (as seen from the injection side) the metal insert to form the stiffening ribs.

Thus, the front of the molten plastic is accelerated from the inner side of the metal insert facing away from the injection side with respect to the molten front moving away from the injection on the outer side of the metal insert which is retarded. This prevents the metal insert from being pressed against the walls of the injection mold limiting the flow outward because of a higher hydraulic pressure of the molten plastic on its inner side. Thus, a flawless, sealed plastic coating is ensured on the injection side of the metal insert since the outer side of the finished lightweight component thus formed in its installed position is the visible view side, which has considerable significance to the appearance of the lightweight component.

Advantageous configuration characteristics of the invention result from the Dependent claims. The particular configuration of the projections provided at the holes of the metal insert must be mentioned here that allows positioning of the plane extending from the opening of each hole to be perpendicular, or almost perpendicular, to the base surface of the metal insert. Particularly, the approximately clam-shaped cavity of the hrbs formed as a hollow quarter-sphere allows the molten plastic penetrating through each hole to form a form-fit head within the hollow shape on the concave side of the cavity covered by the clam-lid after hardening. The large number of the opening present in metal insert, and the correspondingly large number of plastic heads formed in this manner ensures a particularly tight, form-fit connection between the plastic and the metal insert.

It is important to note that the present invention is not intended to be limited to a device or method which must satisfy one or more of any stated or implied objects or features of the invention. It is also important to note that the present invention is not limited to the preferred, exemplary, or primary embodiment(s) described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by the following claims.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present invention will be better understood by reading the following detailed description, taken together with the drawings wherein:

FIG. 1 is a cutaway from a metal insert for a lightweight component in according to the present invention;

FIG. 2 is a perspective view of a section of a lightweight component with a metal insert as shown in FIG. 1 provided after three-dimensional deformation, and as seen from the injection side;

FIG. 3 is a perspective view of the lightweight component of FIG. 2 seen from its inner side;

FIG. 4 is a perspective view of another embodiment of a lightweight component essentially as in FIG. 2 illustrating ares of no passage holes in the metal insert; and

FIG. 5 is a perspective view of the lightweight component of FIG. 4 seen from its inner side.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows in detail a section of a metal insert not yet shaped into three dimensions that represents a flat shape, and produced from a steel sheet. A large number of holes 2, namely passage holes, is worked into the steel sheet in a particular manner, as is known in the art, whereby the metal insert 1 possesses a sieve-like structure. The metal insert 1 is formed similar to a kitchen grater, and possesses a textured outer side, namely an injection side 4, and a smooth inner side 6 in which the apertures of the penetrating holes 2 are located.

Projections 3 are raised from the metal sheet of the metal insert 1 on the outer injection side 4 that approximate the shape of a hollow quarter sphere. Thus, the projections 3 have the approximate shape of an open clam, whereby the half-sided clam openings 8 on the injection side 4 form the apertures of the passage holes 2. The aperture planes of the holes 2 on the injection side 4 stand almost perpendicular to the base surface of the metal insert 1, whereby these planes of the holes 8 may be arranged to be parallel or not. This depends on how one wishes to control the flow direction of the molten plastic that is injected to coat the metal insert 1 into an injection mold into which the metal insert 1 is placed after three-dimensional deformation. This involves archival of a complete coating of the metal insert 1 and allowing the molten plastic simultaneously to flow through the holes 2 in the metal insert 1 in order subsequently to fill channels in the inner side 6 of the metal insert 1.

In one embodiment, stiffening ribs 7 visible in FIG. 3 are formed from the plastic coating the metal insert 1. One of the options of configuring the apertures 8 of the holes 2 on the injection side 4 of the metal insert 1 consists, as FIG. 1 show, of positioning the planes of the apertures 8 in two directions crossing each other. Further, the multiple holes 2, and correspondingly the multiple projections 3 on the injection side 4 of the metal insert 1, are positioned at regular distribution in intermeshing rows to the extent that the areas to be coated are involved.

FIGS. 2 and 3 show a finished lightweight component in which the metal insert 1, as shown in FIG. 1, has been deformed through three dimensions before being coated using injection molding, whereby concave cavities with hollow areas result on the inner side 6 of the metal insert 1 to support the stiffening ribs 7. FIG. 1 shows a view of the lightweight component including a section of the metal insert 1 not yet coated and seen from the injection side 4, and one may recognize that the plastic coating 5 completely covers the injection side 4 of the metal insert 1. Since the plastic coating is thicker than the projections 3 of the metal insert 1, the crowns of the projections 3 of the metal insert 1 cannot be seen on the view side of the lightweight component formed by the injection side 4 in the area of the plastic surface.

This may be provided differently in the view side of the lightweight component for design reasons in that one makes the plastic coating as thick as the height of the projections 3 of the metal insert 1. Both for design reasons and because of the flow characteristics of the molten plastic during the injection process, the projections surrounding the holes 2 may also be provided on the inner side 6 of the metal insert 1. In this manner, the sieve-like metal insert 1 may partially provide a different flow resistance for the molten plastic that is not merely dependent on the aperture width and direction of the holes 2, but rather also on the positioning of the projections 3.

As FIG. 3 shows, the positioning of the stiffening ribs 7 is basically independent of the hole configuration of the metal insert 1, of which a section here has also been left visible. The stiffening ribs 7 have such connecting cross-sections at the metal insert 1 that a number, or large number, of holes 2, or their apertures are covered on the inner side 6 of the metal insert 1. Thus, the connection points of the stiffening inserts 7 may be provided at any point on the metal insert 1. The only pre-requisite is that the sieve structure of the metal insert 1 with the holes 2 and the projections 3 is present on each connection point. The metal insert 1 may also particularly possess edge or end areas that do not possess the sieve structure, and accordingly are not coated with the plastic material. These areas serve principally to form or mount the attachment medium by means of which the lightweight component is mounted to the chassis of the automobile involved, for example, or by means of whose fittings the lightweight component is mounted in other applications.

FIGS. 4 and 5 show a slightly-modified embodiment of a lightweight component in which the perforation, i.e., the holes 2 with their projections 3 does not extend over the entire surface of the metal insert 1. Thus, the metal insert 1 possesses a perforated wall section 9 and a closed wall section 10. The latter is correspondingly not provided with such holes that enable a connection of the plastic structures to the injection side 4 and the inner side 6 of the metal insert 1.

The enclosed wall section 10 of the metal insert 1 extends at least around the injected plastic 11 that is located on the outer side 4 of the lightweight component, and thus also onto the outer side of the metal insert 1. Likewise, the enclosed wall section 10 of the metal insert 1 may also be provided at such a location at which a flow channel within the plastic injection mold opens, and from which a plastic front spreads out over the metal insert 1. The reason is to guide the front of the molten plastic first via a specified route over the outer side 4 of the metal insert 1 when the metal insert 1 is coated. Depending on the configuration of the lightweight component, it may be advantageous not to displace or deform the metal insert 1 within the injection mold.

The enclosed wall section 10 of the metal insert 1 may also serve, however, to allow the molten plastic during the injection process to flow only from one or more specific directions and in predetermined amounts into the channels of the injection mold in which the stiffening ribs 7 are formed. In this case, the enclosed wall section 10 of the metal insert 1 covers the area in which the stiffening ribs 7 are not yet bound to the inner side 6 of the metal insert 1. Resultantly, the plastic coating 5 is formed on the inner side 6 of the metal insert 1 only in the area of the perforated wall sections 9, and not on the inner side 12 of the enclosed wall section 10.

Correspondingly, the form-fit connection of the stiffening inserts 7 exists within the finished lightweight component only at the wall sections 9 of the metal insert 1 provided with holes 2. As a rule, these perforated wall sections 9 exist on opposing sides of the hollow areas formed in the metal insert 1. Thus, in spite of the missing connection of the stiffening ribs 7 to the enclosed wall sections 10 of the metal insert 1, a high degree of stiffness is achieved for the lightweight component.

Finally, the enclosed wall sections 10 of the metal insert 1 also contributes to providing a particularly smooth surface of the plastic coating 5 on the outer side 4 of the lightweight component in the pertinent areas. It is in the mounted position of the lightweight component that this area is positioned on the visible side, which involves the crown area of the hollow areas formed into the shaped part. In this area, a U-shaped cross-section of the lightweight component is provided whereby the U aperture is positioned away from the visible side of the lightweight component in its mounted position.

As mentioned above, the present invention is not intended to be limited to a device or method which must satisfy one or more of any stated or implied objects or features of the invention and should not be limited to the preferred, exemplary, or primary embodiment(s) described herein. Modifications and substitutions by one of ordinary skill in the art are considered to be within the scope of the present invention, which is not to be limited except by the following claims. 

1. A lightweight component that is resistant to flex and torsion in the shape of a flat, three-dimensionally deformed shape with a metal insert possessing penetrating holes along with projections next to them, that includes the flat, three-dimensionally deformed shape, and with stiffening ribs that are positioned at least on one side on the flat shape within hollow areas formed by the three-dimensional shape, whereby the metal insert is spray-coated from an injection side with a plastic that forms a plastic coating on the injection side and that forms the stiffening ribs by flowing through the penetrating holes of the metal insert, characterized in that the penetrating holes of the metal insert are positioned in large numbers with regular distribution in the the projections at each of the penetrating holes of the metal insert correspond at least to the thickness of the plastic coating, and that the stiffening ribs possess a fitting cross-section that extends over many, or a large number, of the penetrating holes in the metal insert.
 2. A lightweight component as in claim 1, characterized in that the injection side is the visible side when in the mounted position on which the thickness of the plastic coating is greater than the height of the projections at the holes, and correspondingly the visible side in the coated area is completely formed by the plastic.
 3. A lightweight component as in claim 2, characterized in that the surface of the plastic flowing through the holes of the metal insert lies on the inner side facing away from the injection side to bond with it, or extends over it.
 4. A lightweight component as in claim 1, characterized in that the projections are recesses hollowed out from the basic surface of the metal insert that possess half-sided apertures that form the apertures of the holes in the metal insert.
 5. A lightweight component as in claim 4, characterized in that the projections are approximately the shape of a hollow quarter sphere.
 6. A lightweight component as in claim 4, characterized in that the apertures of the holes created from the metal insert corresponding to the projections on the injection side each lies in a plane that is perpendicular, or almost perpendicular, to the base surface of the metal insert.
 7. A lightweight component as in claim 4, characterized in that the apertures of the holes at the projections hollowed out from the metal insert lie in planes that are parallel with one another.
 8. A lightweight component as in claim 4, characterized in that the apertures of the holes at the projections hollowed out from the metal insert are divided into two or more groups whereby the apertures of the holes of one group lie in planes that are parallel with one another, and the planes of the holes of the group are at an angle to one another.
 9. A lightweight component as in claim 7, characterized in that the apertures of the holes at the hollowed-out projections of the metal insert lying in parallel planes to the base surface of the metal insert point in the same direction perpendicular to the plane of each hole and parallel, or almost parallel, base surface of the metal insert.
 10. A lightweight component as in claim 1, characterized in that the projections at the holes are partially positioned on the inner side of the metal insert.
 11. A lightweight component as in claim 1, characterized in that the metal insert includes coated as well as uncoated areas and the sieve structure with holes and the projections are present only in the coated areas.
 12. A lightweight component as in claim 1, characterized in that the metal insert possesses an enclosed wall section in the vicinity of at least one injection point on the injection side, or of a mouth point of a flow channel for the plastic that correspondingly transforms into a wall section provided with the holes at which the stiffening ribs attach to the inner side of the metal insert.
 13. A plastic coated, metal core, lightweight component comprising: a metal insert having a plastic coating application side, said metal insert including a plurality of holes penetrating through said plastic coating application side of said metal insert and disposed about at least a portion of said metal insert, and a corresponding plurality of projections on a side opposite from said plastic coating application side, said projections located proximate said holes and having approximately the shape of a hollow quarter sphere; and a plastic coating applied to said plastic coating application side of said metal insert and covering at least a portion of said metal insert, and whereby the plastic coating flowing through at least some of said penetrating holes in the metal insert forms stiffening ribs. 